Conventional pallets include a base layer and a cargo layer separated therefrom by support blocks. Traditionally, the base and cargo layers respectively have end deck boards of a common thickness assembled on connector boards that run the full length or width of the pallet. The end deck boards are nailed through the connector boards into the support blocks to build the primary structure of the pallet. Intermediate deck boards are placed between the end deck boards. The end deck boards are also known as lead boards.
To move the pallet with cargo thereon, forklift tines are inserted into the gaps between the base and cargo layers. If the forklift is not stopped in time, the forklift may crash into one of the end deck boards of the pallet. The end deck board may not be able to withstand such an impact over time. Accidents such as this weaken the pallet and greatly shorten the lifespan of the pallet, thereby causing the pallet to be repaired more frequently and/or removed from service long before its anticipated life cycle has been reached.
In an effort to improve pallet durability, an intermediate deck board may butt up against an end deck board to help resist impacts from material handling equipment. While this technique is effective at generating more resistance, the effect of a failure is often two boards being broken instead of just one.
Another approach is disclosed in U.S. Pat. No. 4,220,099 to Marchesano. The ′099 patent discloses a pallet comprising at least two runners, and a plurality of deck boards or stringers coupled to the runners. In particular, the end deck boards in the cargo layer are dadoed or undercut into the runners to thereby strengthen the pallet. The end deck boards in the base layer are received in recessed portions of the runners so that they butt up against the runners. This may be effective in strengthening the pallet, but undercutting the end deck boards for the cargo layer and the corresponding runners is a time consuming process, and as a result, adds to the expense of building a pallet.
The use of nail plates to strengthen wood pallet joints is disclosed in U.S. Pat. No. 7,056,074 to Bas. The nail plates are placed between an upper surface of the support blocks and boards in the cargo layer, and between a lower surface of the support blocks and boards in the base layer. Each nail plate includes projections extending from upper and lower surfaces thereof, and a center opening for receiving a connecting device. A respective connecting device is used for each support block to couple the corresponding boards in the cargo and base layers to each support block, with the corresponding nail plates penetrating into opposing wood surfaces. This may also be effective in strengthening the pallet, but positioning the nail plates so that the center openings are aligned for receiving the connecting devices is critical, and as a result, adds to the expense of building a pallet.